DC Fire and EMS personnel were called shortly after midnight to a two-story apartment building in the 300 block of Seaton Place SE, where acting Fire Chief Anthony Kelleher said crews were met by flames on all floors, and through the roof.
Flames extended to a neighboring building and another building across the alley was also exposed, he added.
Upwards of 100 firefighters responded to the building to help battle the blaze, though no injuries were reported once the fire was declared under control.
In total, 17 people and dog were displaced from 10 units. They are now being assisted by the Red Cross, Ward 5 Council Office, and DC Office of Community Relations and Services.
The cause and origin of the fire remains under investigation.
Check Daily Voice for updates.
Want breaking news in the DMV as it happens, or want to contribute? Join the DMV All Incidents Facebook group.
Click here to follow Daily Voice Arlington and receive free news updates.